TCP / IP network communication program design
College of Mathematics and Computer Science, Hubei University (430062) Demodes
This article introduces the object-oriented design method for TCP / IP network applications, and gives it
Program instances developed in Visual C 4.2 MFC in the Windows 95 environment.
1 Sockets with Winsock 95
Winsock 95 is developed on the basis of UNIX Sockets and Windows Sockets
Come. Sockets is originally BSD 4.3BSD UNI for UNIX support Internet communication
The API in the X version, which uses the communication mechanism of the customer-server mode to make the network client and
Server party achieves links and data exchange between networks via Sockets; Win Dows SOC
The KETS description defines a network programming interface of Microsoft Windows, which is Window.
S TCP / IP provides a BSD-type socket, except for 4.3BSD UNIX Sockets.
Recliscount, also includes an expansion file, implementing Windows in a set of additional APIs (mini
Piece-driven programming style; Winsock 95 is in Microso FT Windows 95
The interface for web application design. Windows 95 TC in the Internet domain domain
The P / IP protocol defines the Winsock 95 network programming specification and dissolves in many new features. MFC
The corresponding CSOCK ET class is provided to enable network communication.
2 Sockets Programming Principles
Sockets simultaneously supports data streams SOCKETS and Datashers SOCKETS.
Below is a process block diagram of a communication connection using Socket. Fig. 1 is a facing
Timing diagram, Figure 2 is a timing chart without connection.
figure 1
figure 2
As can be seen from the figure, the relationship between the customer and the server is asymmetrical. For TCP C / S,
The server starts first, then starts the customer with the server to establish a connection at a certain moment. service
Both the server must start calling socket () to create a socket, and then serve
Call bind () to bundle the socket with a local network address, then call Liste
n () makes the socket in a passive ready-to-receive state, and specifies its request queue.
Degree, then the server can call accept () to receive the client connection. Customer opens the set
After the word, the connection can be established by calling the CONNE CT () and the server. After the connection is established,
Data can be sent and received between the client and the server. Finally, to be transmitted
End, the two parties call the CloseSocket () closing the socket. For UDP C / S, customers do not
Establish a connection with the server, but only send a server address to the server.
Datagram. Similarly, the server does not receive a connection from the client, just call the function RE
CVFROM, waiting for data from the client. The protocol address returned in accordance with RECVFROM and
Data report, the server can send a response to the customer.
3 Winsock 95 programming method
Using Visual C 4.2 with MFC to realize network programming in Windows 95, mainly
Use the CSocket class and its related member functions:
(1) BOOL CREATE (uint nsocketport = 0, int NSockettype = SOCK_
Stream, Long Leve NT = fd_read | fd_write | fd_ood | fd_accept | fd_con
NECT | fd_close |, lpctstr | lpszsocket address = null
This function is used to build a socket.
(2) BOOL BIND (Uint NSocketport, LPCTSTR LPSZSSOCKETDESS = N
ULL)
The function of this function is to connect the Socket port with the network address.
(3) BOOL Listen (int NConnectionbackLog = 5)
The function of this function is to wait for the Socket request.
(4) Virtual Bool Accept (CasyncSocket & rConnected Socket,
Socket, SockAddr * lpsock addr = null, int * lpsock addrlen = NULL)
The function of this function is to get the first connection request on the queue and create a one with SO.
Cket The same characteristics socket.
(5) Bool Connect (LPCTSTSTR LPSZHOSTADDRESS, UINT NHOSTPORT)
The function of this function is to make a request. Among them, lpszhostaddress and Nhostport
To accept the network address and socket port number of the request process.
(6) Virtual void close () The function of this function is to close the socket.
Use the above class and member functions, follow these steps to design appropriate communication
program:
Server: Construct → Creat → Bind → Listen → Accept → Send → CLO
SE;
CLIENT: Constuct → Creat → Connect → Receive → Close.
4 program example
We designed a dayt in the Windows 95 environment with Visual C 4.2.
The IME clion program, the list is as follows:
Head file head.h content:
#define IDM_STRAT 200
#define IDM_EDIT 200
Class MainWnd: Public CFrame WND
{public: mainwnd ();
AFX_MSG INT OnCreat (LPCReatestruct);
AFX_MSG Void OnStart (Void);
Declare_MESSAGE_MAP ();
PRIVATE: CSTATIC CSSTATIC;
Cedt lineedit;
CButten StartButton;
Class Pengapp: Public CWINAPP
{public: BOOL INITINSTANCE ();
Source program client.cpp list:
#include
#include
#include "head.h"
Const int nport = 13;
PENGAPP THEAPP;
Main wnd: main wnd ()
{if (! CREATE (NULL, "Communication Program", WS_OVERLAPPEDW
Indow, RectDefaul T)) AFXABORT ();
Int mainwnd: oncreate (lpcreatestruct)
{Rect Rect; SetRect (& RECT, 80, 50, 160, 70);
Create ("Host Name:", WS_CHILD | WS_VISible | SS_LEFT, RECT, THI
S);
SetRect (& RECT, 60, 80, 180, 100);
LineEdit.create (WS_CHILD | WS_VISIBLE | WS_DLGFRAME | ES_LEFT,
Rect, this, IDM_ED IT;
SetRect (& RECT, 100, 120, 140, 140);
StartButton, Create ("Start", WS_CHILD | VS_VISIBLE | BS_PUSHBU
Tton, RECT, THIS, I DM_START);
Return 0;}
Begin_Message_Map (Main Wnd, CFrameWnd)
ON_WM_CREATE ()
ON_BN_CLICKED (IDM_START, ONSTART)
END_MESSAGE_MAP ()
Bool Controlapp: InitInstance ()
{m_pmainwnd = new main wnd ();
m_pmainwnd → showwindow (m_ncmdshow);
M_PMainWnd → UpdateWindow ();
Return;}
Void main wnd: onstart (void)
{CSocket TimeClient;
IF (! AFXSocketinit ()) MessageBox ("WindowsSocket Initial
Failed! "," Receiv E ", MB_ICONSTOP);
IF (! timeclient.create ()) MessageBox ("ReceiveSocket Crea
TE failed "," Rece Ive ", MB_i (ON) STOP);
Else TimeClient.connect (straddr, nport);
TimeClient.ReceiveFrom (CSReceiveText, Cscounts, Lineedit.g
ETWINTEXT, NPORT)
MessageBox (TimeClient.csReceiveText);
TimeClient.close ();
